Such apparatuses are well known. Some of them are provided with a conducting cup which is generally cylindrical in shape and which is connected to a current inlet, a winding disposed inside said cup in order to produce a magnetic field along the axis of the cup and having one end connected to the cup, conducting core connected to the other end of the winding and situated in the center of the winding, and a circuit-breaking contact disposed ahead of the coil relative to said cup within the magnetic field produced thereby and electrically connected to said core. Special means must be provided to prevent the coil from exploding under the effect of a short circuit current when the switch is opened.
The invention seeks to provide means which are simple and easy to implement for imparting a high degree of mechanical strength to the winding of the coil. These means incidentally make it possible to establish electrical contact with each of the ends of the winding in a manner which is both simple and reliable.